Lightning-rod ball



(No Model.)

E. K. HUM. LIGHTNING ROD BALL No. 556,984. Patented Mar. 24, 1896.

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flTTOFF/VEY UNITED STATES PATENT OFFICE.

EDIVARD K. HUM, OF PITTSBURG, PENNSYLVANIA.

LIGHTNING-ROD BALL.

SPECIFICATION forming part of Letters Patent No. 556,984, dated March 24, 1896.

Application filed January 5,1895. Serial No. 533,961. (No model.)

To all whom it may concern.-

Be it known that I, EDWARD K. HUM, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented or discovered new and useful Improvements in Lightning-Rod Balls, of which the following is a specification.

In the accompanying drawings,which make part of this specification, Figure 1 is a side elevation of a glass ball for lightning-rods. Fig. 2 is a central longitudinal section through the tube of same and locking-cap, and Fig. 3 a perspective of the locking-cap.

The purpose of my invention, generally stated, is to devise a glass lightning-rod ball which shall retain its coat of quicksilver intact without becoming crazed, streaked or spotted after a brief time as is now the case, and whereby the flanges on the tube and locking-cap may be united to the ball by a strong but harmless cement.

I have chosen as a means to illustrate my invention a lightning-rod ball described in my Patent No. 492,512, issued February 28, 1893, but the principle of my invention is applicable to all glass lightning-rod balls, having a metal or glass tube to receive the rod, which have a silvered surface, nor do I claim here the peculiar mechanical features of the locking-tubes which formed the subject-matter of said recited patent.

Lightning-rod balls have been made of glass with an interior coating of quicksilver in very large quantities and for about sixteen or seventeen years. No practical method, however, heretofore has been devised to protect the quicksilver and the same has invariably become streaked, spotted or crazed from the moisture in the atmosphere, giving the balls a mottled and inferior appearance. Another cause contributing to mar the appearance of the silvering is due to the use of plaster-ofparis or putty in making the joint between the tube of the ball and the ball. The oil from the putty and the lime from the plaster-of-paris will eat away the quicksilver and greatly mar the neat efiect of the ball.

I have discovered a treatment for the ball which will preserve unbroken the coating of quicksilver and also secure a tight joint between the flanges of the tube and the outer surface of the ball without the use of putty or plaster-of-paris.

In the accompanying drawings, which make part of this specification, 1 is a glass ball having the usual openings for the insertion of a tube. These openings are preferably ground off to preserve the true spherical form of the ball after the tube with its flanges is applied.

2 is a metal tube of sufficient length to extend through the ball, and provided with flange 3 at one end. Near its other end it is provided with a short length of female thread 4 preferably pressed therein.

5 is a locking-cap, having flange 6 and spur 7 to engage with thread 4.

The construction thus set out is that described in my recited patent, No. 492,512. Before inserting the tube and locking-cap in position it is customary to plug up the openings in the glass ball after introducing a proper amount of quicksilver, and then shake the ball until the quicksilver has completely coated the inside. The tube and locking-cap are then, in ordinary practice, secured in place and a close joint made between the ball and the flanges of the tube and cap by the use of putty or plaster-of-paris. It is at this point that my invention differs from the prior state of the art. After the quicksilver has been applied I allow it a sufficient time to dry, and then before inserting the tubes dip the ball in asphaltum cut with sufficient turpentine to make the same thin enough to flow evenly upon the quicksilver coating. The ball is then removed and the tube and locking-cap applied in place, when a tight joint will be made by the asphaltum between the flanges of the tube and cap and the outer surface of the ball. The asphaltum is then wiped off the remaining exterior of the ball, while the turpentine in the inside will quickly dry, leaving the quicksilver thoroughly protected with a thin coat of asphaltum. The effect is to give a ball of great brilliancy and uniformity of silvering and farsuperior in appearance to any on the market. peculiar features will also be retained in actual use, for the quicksilver is completely covered, nor is there any material in the joint liable to injure the silver.

If desired, the ball maybe dipped in a thin paint, varnish, or like material instead of the protected and the said flanges united to the 10 asphaltum, but I prefer the latter. ball by a harmless cement.

Having described my invention, I claiin In testimony whereof I have hereunto set Asilvered glass lightning-rodballhaving an my hand this 3d day of January, A. D. 1895; 5 interior coating of asphaltuin, varnish, paint,

or like material over the quicksilver, as Well EDWVARD K. HUM. as between the outer surface of the ball and \Vitnesses:

the flanges of the lightning-rod tube and the \VM. L. PIERCE,

locking-cap whereby both the quicksilver is C. 0. LEE. 

